Research On Reactive Power Optimization Of Power System With Renewable Energy

In order to achieve the goal of energy saving and emission reduction,the energy transformation strategy is being implemented,which makes renewable energy be vigorously developed and utilized in the world.With the government's strong support and the continuous innovation of power generation technology,renewable energy has developed vigorously in the power industry,and its proportion in the power gird is also increasing.However,renewable energy(mainly wind energy and solar energy)is random and fluctuating,which leads to the strong uncertainty and unpredictable of its output power,and has a great impact on the operation of power system.Therefore,how to deal with these uncertainties has become the focus of current research in the optimal operation of power system.In this paper,reactive power optimization of power system is studied.Firstly,in view of the uncertainty of renewable energy output power and load,the distribution characteristics of wind power,solar power system output power and load power are analyzed,and then their probability models are determined.Secondly,in order to take into account the correlation between the output power of renewable energy and obtain the probability density function of the state variables,the probabilistic power flow algorithm based on three-point estimation method is improved by using Nataf transformation and Gram-Charlier series expansion.The analysis of an example shows that the method has high calculation accuracy and efficiency and can be used in practical engineering calculation.Then,based on the traditional reactive power optimization model,a static reactive power optimization model with probability constraints is established.It takes the minimum sum of active power loss expectation and voltage excursion expectation as the objective function,takes into account distribution network reconfiguration and the uncertainty of renewable energy output power and load.The improved Bat Algorithm is used to solve the model.The validity and effectiveness of the optimization model are verified by an example.Finally,on the basis of the static reactive power optimization model,the dynamic reactive power optimization model considering the restriction of the action times of adjustable equipment is established.A time-period decoupling method is used to decouple the model,and the solution method of the static optimization model is used to solve the decoupled model.By comparing the optimization results of the static and dynamic reactive power optimization models,the dynamic reactive power optimization model is proved to be superior.The model can effectively reduce network loss and improve voltage quality even when the action times of adjustable devices is limited,and can provide guidance for the practical optimization operation.